Fixed bug where calling fill on pixmap with active painter would crash.

Calling QPixmap::fill() on a pixmap may in some cases cause the
painter's paint engine pointer to become stale. A subsequent call to
the painter would therefore crash. Now, QPixmap::fill() will print a
warning and return in those cases. I also added a warning in the
documentation of QPixmap::fill().

Task-number: QTBUG-2832
Reviewed-by: Trond

1 files changed, 10 insertions, 0 deletions

diff --git a/src/gui/image/qpixmap.cpp b/src/gui/image/qpixmap.cpp
index 558ae543c9..8133cc0a4d 100644
--- a/src/gui/image/qpixmap.cpp
+++ b/src/gui/image/qpixmap.cpp
@@ -947,6 +947,9 @@ bool QPixmap::doImageIO(QImageWriter *writer, int quality) const
 /*!
     Fills the pixmap with the given \a color.
 
+    The effect of this function is undefined when the pixmap is
+    being painted on.
+
     \sa {QPixmap#Pixmap Transformations}{Pixmap Transformations}
 */
 
@@ -955,6 +958,13 @@ void QPixmap::fill(const QColor &color)
     if (isNull())
         return;
 
+    // Some people are probably already calling fill while a painter is active, so to not break
+    // their programs, only print a warning and return when the fill operation could cause a crash.
+    if (paintingActive() && (color.alpha() != 255) && !hasAlphaChannel()) {
+        qWarning("QPixmap::fill: Cannot fill while pixmap is being painted on");
+        return;
+    }
+
     detach();
     data->fill(color);
 }